Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.
An oxide XO2 has a vapour density of 32. What is the atomic mass of X?
20
32
14
12
Correct answer is B
Molecular mass = vapour density X2
Mm of XO2 = x + 16(2) = x + 32
vapour density = 32
∴ x + 32 = 32 × 2
x + 32 = 64
x = 64 - 32
x = 32
∴ the relative molecular mass of X is 32
Relative molecular mass = vapour density × 2
According to Charle's law, the volume of a gas becomes zero at
−100°c
−273°c
−373°c
0°c
Correct answer is B
Where −273°c = OK
i.e −273°c + 273 = OK
At zero kelvin, the volume of a gas becomes zero.
The carbon atoms on ethane are
sp2 hybridized
sp3 hybridized
sp4 hybridized
sp hybridized
Correct answer is B
Alkane's family are sp3 hybridized
0.1
0.5
2.0
4.0
Correct answer is C
The rate of dimension of a gas inversely proportional to the square root of its molecular mass or its density, which is Graham's Law of diffusion of gas.
R ∝ \(\frac{1}{\sqrt{Mm}}\) or R ∝ \(\frac{1}{\sqrt{D}}\)
Dx = 0.5gdm-3, Dy = 2gdm-3
R= \(\frac{K}{\sqrt{D}}\)
R\(\sqrt{D}\) = k
R1\(\sqrt{D_1}\) = R1\(\sqrt{D_2}\)
Rx\(\sqrt{D_x}\) = Ry\(\sqrt{D_y}\)
\(\frac{R_x}{R_y}\) = \(\frac{\sqrt{D_y}}{\sqrt{D_x}}\)
= \(\frac{\sqrt{2}}{\sqrt{0.5}}\)
= 2.0
The reddish–brown rust on iron roofing sheets consists of
Fe3 + (H2O)6
FeO.H2O
Fe2O3.XH2O
Fe3O4.2H22O
Correct answer is C
Iron [Fe] reacts with H2 in the presence of oxygen to form a rust.
4Fe + 3O2 → 2 Fe2O2
Fe2O3 + H2O → Fe2O3.H2O